Method and arrangement for allocation of resources in a radio communication system

ABSTRACT

A method and arrangement for fair control of resources amongst users with different instantaneous throughputs in a radio communication system such as a UMTS system. Respective indications of users among whom resources are to be allocated are placed in a ‘round robin’ queue ( 200 ) and each user whose indication is at the head of the queue is allocated a number of resource units as a function of: β, a predetermined parameter determining the extent to which a fixed number of resource units should be allocated to the user and the extent to which a fixed volume of data should be transferred from/to the user; φ, the volume of data that the user is allowed to transfer if β=1; λ, the number of resource units that can be allocated if β=0; and θ, the number of information bits per resource unit that can be transferred to/from the user.  
     This provides the following advantages:  
     the resources can be allocated in the manner chosen by the operator.  
     the function requires very few input parameters, and so is simple to operate.

FIELD OF THE INVENTION

[0001] This invention relates to packet-based radio communicationsystems employing shared channels for data transfer.

BACKGROUND OF THE INVENTION

[0002] In a system employing shared channels, a portion of the sharedresource is allocated to user equipment (UEs) on a round-by-round basis.The amount of the shared resource allocated to a user is measured in thesmallest individual unit of the shared resource that can be allocated;this is called a resource unit.

[0003] Depending on the prevailing radio channel conditions the numberof information bits that can be transferred in each resource unit willvary. It is likely that in a cellular system the number of bitstransferred per resource unit will vary greatly across the coverage areaof the cell.

[0004] In this environment it is desirable to provide the same overallthroughput to packet users regardless of the radio conditions theyexperience.

[0005] Conventionally either:

[0006] The number resource units allocated per round of allocation isfixed, regardless of the number of information bits that can betransferred in each resource unit. or

[0007] Resource units are allocated so that an equal volume of data istransferred to each user in each round of allocation.

[0008] Allocating a fixed number of resource units per round ofallocation to all users has the disadvantage that some users willexperience very much poorer throughputs than others. However, thismethod has the advantage that overall throughput in the cell will bemaximised.

[0009] Allocating the appropriate number of resources so that a fixedvolume of data is transferred has the disadvantage that overall cellthroughput is reduced. However, this method has the advantage ofproviding even throughput to all users irrespective of their channelconditions.

[0010] The optimum condition required by the operator of the system maylie somewhere between these two extremes.

[0011] A need therefore exists for control of resources amongst userswith different instantaneous throughputs wherein the abovementioneddisadvantage(s) may be alleviated.

STATEMENT OF INVENTION

[0012] n accordance with a first aspect of the present invention thereis provided a method for allocation of resources amongst users in aradio communication system, the method comprising:

[0013] storing respective indications of users among whom resources areto be allocated; and

[0014] repetitively allocating predefined resource units in turn to eachuser whose indication is stored, the number, γ, of resource unitsallocated to a user being a function of:

[0015] φ, the volume of data that the user is allowed to transfer if afixed volume of data is transferred;

[0016] λ, the number of resource units that can be allocated to a userif a fixed number of resource units is allocated to the user;

[0017] θ, the number of information bits per resource unit that can betransferred to/from the user; and

[0018] β, a predetermined parameter determining the extent to which afixed number of resource units should be allocated to the user and theextent to which a fixed volume of data should be transferred from/to theuser.

[0019] In accordance with a second aspect of the present invention thereis provided an arrangement for allocation of resources amongst users ina radio communication system, the arrangement comprising:

[0020] means for storing respective indications of users among whomresources are to be allocated; and

[0021] means for repetitively allocating predefined resource units inturn to each user whose indication is stored, the number, γ, of resourceunits allocated to a user being a function of:

[0022] φ, the volume of data that the user is allowed to transfer if afixed volume of data is transferred;

[0023] λ, the number of resource units that can be allocated to a userif a fixed number of resource units is allocated to the user;

[0024] θ, the number of information bits per resource unit that can betransferred to/from the user; and

[0025] β, a predetermined parameter determining the extent to which afixed number of resource units should be allocated to the user and theextent to which a fixed volume of data should be transferred from/to theuser.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] One method and arrangement for ‘fair’ control of resources in aradio communication system amongst users with different instantaneousthroughputs incorporating the present invention will now be described,by way of example only, with reference to the accompanying drawings, inwhich:

[0027]FIG. 1 shows a block diagrammatic representation of a UMTS systemin which the present invention is used; and

[0028]FIG. 2 depicts schematically a ‘round robin’ queue scheme used inresource allocation in accordance with the present invention;

[0029]FIG. 3 shows a possible implementation of the queue scheme of FIG.2; and

[0030]FIG. 4 shows a block diagrammatic representation of an RNC elementof the system of FIG. 1 incorporating the resource allocationarrangement of FIG. 2.

DESCRIPTION OF PREFERRED EMBODIMENT

[0031] Referring firstly to FIG. 1, a typical, standard UMTS network(100) is conveniently considered as comprising: a user equipment domain(110), made up of a user SIM (USIM) domain (120) and a mobile equipmentdomain (130); and an infrastructure domain (140), made up of an accessnetwork domain (150), and a core network domain (160), which is in turnmade up of a serving network domain (170) and a transit network domain(180) and a home network domain (190).

[0032] In the mobile equipment domain (130), user equipment UE (130A)receives data from a user SIM (120A) in the USIM domain 120 via thewired Cu interface. The UE (130A) communicates data with a Node B (150A)in the network access domain (150) via the wireless Uu interface. Withinthe network access domain (150), the Node B (150A) communicates with aradio network controller or RNC (150B) via the Iub interface. The RNC(150B) commmunicates with other RNC's (not shown) via the Iur interface.The RNC (150B) communicates with a SGSN (170A) in the serving networkdomain (170) via the Iu interface. Within the serving network domain(170), the SGSN (170A) communicates with a GGSN (170B) via the Gninterface, and the SGSN (170A) communicates with a VLR server (170C) viathe Gs interface. The SGSN (170A) communicates with an HLR server (190A)in the home network domain (190) via the Zu interface. The GGSN (170B)communicates with public data network (180A) in the transit networkdomain (180) via the Yu interface.

[0033] Thus, the elements RNC (150B), SGSN (170A) and GGSN (170B) areconventionally provided as discrete and separate units (on their ownrespective software/hardware platforms) divided across the accessnetwork domain (150) and the serving network domain (170), as shown theFIG. 1.

[0034] The RNC (150B) is the UTRAN (UMTS Terrestrial Radio AccessNetwork) element responsible for the control and allocation of resourcesfor numerous Node B's (150A); typically 50 to 100 Node B's may becontrolled by one RNC. The RNC also provides reliable delivery of usertraffic over the air interfaces. RNC's communicate with each other (viathe interface Iur) to support handover and macrodiversity.

[0035] The SGSN (170A) is the UMTS Core Network element responsible forSession Control and interface to the Location Registers (HLR and VLR).The SGSN is a large centralized controller for many RNCs.

[0036] The GGSN (170B) is the UMTS Core Network element responsible forconcentrating and tunnelling user data within the core packet network tothe ultimate destination (e.g., internet service provider—ISP).

[0037] The present invention, at least in its preferred embodiment, usesa ‘round robin’ queuing mechanism in allocating resources to users.‘Round robin’ is a well-known scheduling technique in which processesare activated in a fixed cyclic order.

[0038] Referring now also to FIG. 2, which depicts a ‘round robin’ queueused for resource allocation. As users arrive, i.e., when a user hasdata to transfer, a number representing the user is stored or placed atthe tail of a queue 200. In each round of allocation, resources areallocated to a user at the head of the queue. When the user at the headof the queue has been allocated a fixed amount of resource, γ, that useris returned to the tail of the queue, and the number of the next usermoves to the head of the queue. Thus, it will be appreciated, each usernumber moves through the queue 200 in FIFO (first-in, first-out) manner.

[0039] In keeping with the present invention, a fairness parameter, β,is defined that allows an optimum condition between allocating even,overall throughput to users and allocating even numbers of resourceunits to users.

[0040] When β=0 then irrespective of the number of information bits perresource unit that can be transferred to/from the user's UE, a fixednumber of resource units will be allocated to the user whose number isat the head of the queue.

[0041] When β=1 then a fixed volume of data is transferred from/to a UEwhose number is at the head of the queue.

[0042] β can take any value between 0 and 1. When it is at anintermediate value then a compromise is effected between a fixed numberof resource units being allocated to the user and a fixed volume of databeing transferred from/to the UE.

[0043] Let γ be the overall number of resource units that can beallocated to a user when at the head of the ‘round robin’ queue when thescheme described is used.

[0044] Let Φ be the volume of data that a user is allowed to transferwhen at the head of the ‘round robin’ queue if β is set to 1.

[0045] Let λ be the number of resource units that can be allocated to auser when at the head of the ‘round robin’ queue if β is set to 0.

[0046] Let θ be the number of information bits per resource unit thatcan be transferred to/from the UE. This information is available foreach UE in the system.

[0047] The number of resource units that are allocated to a user at thehead of the queue is now calculated using the function shown below$\begin{matrix}{\gamma = {{{\left( {1 - \beta} \right)*\lambda} + {\beta \left( \frac{\varphi}{\theta} \right)}}}} & (1)\end{matrix}$

[0048] Referring now also to FIG. 3, a possible implementation of theFIFO queue 200 includes a block of RAM semiconductor memory 210 having anumber of memory locations of which four, 220, 230, 240 & 250, areshown. A register 260 is used to hold a value pointing to the memorylocation in the RAM 210 which constitutes the head of the queue. Witheach round of resource allocation, the value in the register 260 isdecremented to point to the previous memory location (e.g., beforedecrementing the register 260 points to memory location 250, and afterdecrementing the register 260 points to memory location 240 as shown).The user whose number is in the memory location at the head of the queueis allocated a fixed amount of resource, γ, in accordance with theformula (1) as described above—this is depicted at 300.

[0049] It will be understood that when the register 260 points to thememory location 220, after decrementing the register will point to thememory location 260, so that in this way the queue implemented by theRAM 210 and pointer register 260 will operate in ‘wrap-around’ manner.Also, it will be understood that the number of the user to whomresources have been allocated will automatically be moved to the tail ofthe queue when the register 260 is decremented to point to the previousmemory location. Further, it will be understood that when a new usernumber is to be added to the tail of the queue, the user number isinserted at the next memory location beyond that pointed to by theregister 260 (e.g., if the register 260 points to memory location 240 asshown, then the tail of the queue is at memory location 250).

[0050] In keeping with the present invention, the queue arrangement 200and resource allocation calculation mechanism 300 may conveniently beprovided in the RNC 150B, within the radio access network, as shown inFIG. 4.

[0051] It will be understood that the above scheme for ‘fair’ control ofresources allows users with different instantaneous throughputs to besuccessfully accommodated.

[0052] It will be appreciated that the fair resource allocation schemedescribed above provides the advantage that resources may be allocatedin the manner chosen by the operator (dependent on choice of the valueβ). This can be anywhere between the extremes of allocating a fixednumber of resource units to all users (resulting in maximum overall cellthroughput) and allocating resource units so as to transfer a fixednumber of information bits (resulting in the same overall throughput forall users).

[0053] It will also be appreciated that the formula used in equation (1)above requires very few input parameters, the only knowledge requiredbeing the number of information bits per resource unit.

[0054] It will be appreciated that the method described above forallocating resources among with different instantaneous throughputs maybe carried out principally in software running on a processor (notshown), and that the software may be provided as a computer programelement carried on any suitable data carrier (also not shown) such as amagnetic or optical computer disc.

[0055] It will be also be appreciated that the arrangement describedabove for allocating resources among with different instantaneousthroughputs may be provided in an integrated circuit (not shown) such asan FPGA (Field Programmable Gate Array) or ASIC (Application SpecificIntegrated Circuit).

1. A method for allocation of resources amongst users in a radiocommunication system, the method comprising: storing respectiveindications of users among whom resources are to be allocated; andrepetitively allocating predefined resource units in turn to each userwhose indication is stored, the number, γ, of resource units allocatedto a user being a function of: φ, the volume of data that the user isallowed to transfer if a fixed volume of data is transferred; λ, thenumber of resource units that can be allocated to a user if a fixednumber of resource units is allocated to the user; θ, the number ofinformation bits per resource unit that can be transferred to/from theuser; and β, a predetermined parameter determining the extent to which afixed number of resource units should be allocated to the user and theextent to which a fixed volume of data should be transferred from/to theuser.
 2. The method of claim 1, wherein the number, γ, of resource unitsallocated to a user is substantially equal to${{{\left( {1 - \beta} \right)*\lambda} + {\beta \left( \frac{\varphi}{\theta} \right)}}}.$


3. The method of claim 1 wherein the step of storing respectiveindications of users among whom resources are to be allocated comprisesstoring the indications in a FIFO queue.
 4. The method of claim 1wherein the step of storing respective indications of users among whomresources are to be allocated comprises storing the indications in RAMmemory with a pointer register.
 5. The method of claim 1 performed in aradio network controller of the system.
 6. The method of claim 1 whereinthe radio communication system is a UMTS system.
 7. An arrangement forallocation of resources amongst users in a radio communication system,the arrangement comprising: means for storing respective indications ofusers among whom resources are to be allocated; and means forrepetitively allocating predefined resource units in turn to each userwhose indication is stored, the number, γ, of resource units allocatedto a user being a function of: φ, the volume of data that the user isallowed to transfer if a fixed volume of data is transferred; λ, thenumber of resource units that can be allocated to a user if a fixednumber of resource units is allocated to the user; θ, the number ofinformation bits per resource unit that can be transferred to/from theuser; and β, a predetermined parameter determining the extent to which afixed number of resource units should be allocated to the user and theextent to which a fixed volume of data should be transferred from/to theuser.
 8. The arrangement of claim 7, wherein the number, γ, of resourceunits allocated to a user is substantially equal to${{{\left( {1 - \beta} \right)*\lambda} + {\beta \left( \frac{\varphi}{\theta} \right)}}}.$


9. The arrangement of claim 7 wherein the means for storing respectiveindications of users among whom resources are to be allocated comprisesa FIFO queue.
 10. The arrangement of claim 7 wherein the means forstoring respective indications of users among whom resources are to beallocated comprises RAM memory with a pointer register.
 11. Thearrangement of claim 7 wherein the radio communication system is a UMTSsystem.
 12. A radio network controller for a radio communication system,the radio network controller containing the arrangement of claim
 7. 13.A computer program element comprising computer program means forperforming substantially the method of claim
 1. 14. An integratedcircuit comprising the arrangement of claim 7.